Longitudinal Studies and Older Adults Cohorts

Longitudinal studiesLongitudinal studies are a source of fundamental evidence of multi-factor changes over time, especially those that have contributed to understanding the aging processAging process through researchResearch questions related to the course or prognosis of physical or cognitive functioning of the older adultsOlder adults or exposure to comorbidity, health conditions, geriatric syndromesGeriatric syndromes and negative or positive factors that have influenced the multiple events towards healthy or pathological agingAging. However, these studies have significant methodological challenges to employing follow-up with repeated measures or changes over prolonged periods, especially with the loss of participants due different causes that risk the validity of informationInformation and the generalization of the results. The complexityComplexity of different longitudinal studiesLongitudinal studies motivated the realization of this chapter, where we discussed the role of the longitudinal studiesLongitudinal studies on agingAging, starting with methodological concepts and the importance of the different studies related to time or exposure of study as the classic cohort designCohort design. We also present a review of nationally representative population-based longitudinal studiesLongitudinal studies, which enable us to provide examples of scope and methodological implications of high value. Finally, we suggested some analytical strategies to strengthen the validity and generalization of results.